A polymeric micelle type drug, in which a hydrophobic drug is chemically bound to a block copolymer through a covalent bond, was successfully constructed and applied by the present inventors for a patent in Japanese Patent Application No. 116,082/89. In spite of the fact that this prior polymeric micelle type drug is extremely superior as the means of administrating a hydrophobic drug, the combination of hydrophobic drug and block copolymer is disadvantageously limited because its preparation requires functional groups for chemically binding a hydrophobic drug to a block copolymer.
Under the circumstances, however, no development has been made in a method of physically trapping hydrophobic drugs so as to incorporate them in the inner core of polymeric micelle or in a drug carrier for such a method.
The present inventors have tried to develop a physical trapping type polymeric micelle drug, in order to solve the above disadvantage of the chemical bond type polymeric micelle drug. The present inventors, as a result of their eager research, succeeded in preparing a polymeric micelle type drug applicable to a wide variety of combinations of hydrophobic drugs and block copolymer by constructing a polymeric micelle from a drug carrier composed of a block copolymer having hydrophilic and hydrophobic segments and then permitting hydrophobic drugs to be physically trapped into the hydrophobic inner core of said micelle. The system for trapping drugs, developed by the present inventors, allows a wide variety of hydrophobic drugs to be easily incorporated in the polymeric micelle.